1. Field of the Invention
The present invention relates to a semiconductor device having dummy interconnections, and particularly to a structure of a dummy interconnection having a fuse body in the semiconductor device using multi-level wiring technology and a method for manufacturing the same.
2. Description of the Related Art
In recent years, according to an increasing capacity of memory, the requirement for the dummy interconnections, or xe2x80x9ca fuse circuitxe2x80x9d comprising an array of dummy interconnections, each having a fuse body is growing, and the number of the dummy interconnections (fuse bodies) are swelling year by year. Therefore, an occupying space for the fuse area is also enlarged in a semiconductor chip year by year, and a yield of the product is much influenced by whether or not the required fuse bodies are successfully and selectively blown off.
FIG. 1B and FIG. 1A show examples of conventional dummy interconnection structures. FIG. 1A is a schematic plan view, and FIG. 1B is the sectional view of an array of dummy interconnections, or xe2x80x9cthe fuse circuitxe2x80x9d taken along the line IBxe2x80x94IB in FIG. 1A. As shown in FIG. 1B, insulating layers 5, 6 are formed on a silicon substrate 7, between which a fuse body 2 is arranged. Both longitudinal terminal portions of the fuse body 2 are connected with fuse wirings 3a, 3b via contact plugs 4a, 4b of conductive materials, and there is electrical connection between the longitudinal terminal portions of the fuse body and the fuse wiring 3a, 3b. A fuse window 1, which facilitates to blow the fuse body 2, is formed at the top surface of and in the insulating layer 5. When a given fuse body is irradiated with an laser beam through this fuse window, the irradiated fuse body is blown away, and the electrical connection between the ends of the fuse and the fuse wiring 3a, 3b are brought out of conduction.
Further, FIG. 2A and FIG. 2B show a second conventional example, or other conventional dummy interconnection structures. FIG. 2A shows a schematic plan view of this fuse circuit, and FIG. 2B shows the sectional view of the fuse circuit taken along the line IIBxe2x80x94IIB in FIG. 2A. Here, the same markings are given to the parts corresponding to those in the previous conventional example (first conventional example) shown in FIGS. 1A and 1B. In this second conventional example, to reduce the fuse area, the fuse pitch xe2x80x9cpxe2x80x9d is not only narrowed (however, the fuse pitch xe2x80x9cpxe2x80x9d in FIG. 2B are drawn at the same pitch as in FIG. 1A, for convenience), but widened blow areas 8a are also provided to make the heat of the laser beam to be concentrated thereon and these parts are arranged in a staggered configuration. Such a configuration is proposed so as make possible to selectively blow off the desired fuse bodies in the blow area 8a and also to reduce the fuse pitch xe2x80x9cpxe2x80x9d between adjacent fuse bodies, thereby reducing the fuse area. Here, xe2x80x9cthe fuse areaxe2x80x9d means the area in which the fuse circuit is formed.
However, the first conventional dummy interconnection configuration shown in FIG. 1A and FIG. 1B had a problem that the heat of the laser beam is transported away in the longitudinal direction of the fuse body 2 because the fuse body 2 is comprised of a slim and linear electric conductor.
Also, the second conventional dummy interconnection configuration shown in FIG. 2A and FIG. 2B may have caused damage to adjacent fuse bodies supposed to be not blown off with a very high possibility, this has been a factor of decrease in the manufacturing yield.
An object of the present invention is to provide a semiconductor device allowing fuse bodies to be efficiently and easily blown off without conducting away the heat of laser beam.
Another object of the present invention is, when a fuse body is blown away, to provide a semiconductor device permitting a yield-enhancement without exerting influence on the other fuse bodies scheduled to be not blown.
A further object of the present invention is to provide a semiconductor device with dummy interconnections hardly causing damage to a part which is not irradiated with light even if pitch is narrowed between the fuse bodies.
Another object of the present invention is to provide a semiconductor device permitting to achieve a reduction in a fuse area.
Another object of the present invention is to provide a semiconductor device permitting to easily change a shape of a fuse area and enhance a selectivity and a degree of freedom in arrangements of other circuits in the surroundings of the fuse area.
A further object of the present invention is to provide a method of manufacturing a semiconductor device permitting to easily blow fuse bodies.
An even further object of the present invention is to provide a method of manufacturing a semiconductor device permitting to enhance a manufacturing yield at a time of fuse-blowing.
A first feature of the present invention lies in a semiconductor device having a plurality of dummy interconnections permitting to be selectively disconnected by using laser beam for blowing off fuse bodies. Namely, each dummy interconnection comprising: a first fuse wiring having a first terminal portion; a second fuse wiring having a second terminal portion with a given distance apart from the first terminal portion, being arranged along the same direction as the first fuse wiring is extending; a first connecting member arranged on the first terminal portion; a second connecting member arranged on the second terminal portion; and a fuse body arranged on the first and second connecting members so as to electrically connect the first and second connecting members with each other, having a length not shorter than the given distance and not exceeding a diameter of laser beam used for blowing off the fuse body.
According to the first feature of the present invention, the heat caused by irradiation of the laser beam used for selectively bringing specific dummy interconnections into a disconnected state is not transported away by conduction in the longitudinal direction of the first and second fuse wiring. Further, a possibility becomes low for the light irradiation to cause damage to adjacent fuse bodies scheduled to be not blown, and even if pitch between the fuse bodies is narrowed, a possibility to cause damage to non-irradiated part becomes low. Especially, since it is also possible for the fuse bodies to be two-dimensionally positioned at each vertex of a regular triangle, all the fuse bodies can be kept at an equal interval to other most adjacent fuse bodies. Further, it is also possible to reduce fuse pitch with a minimum fuse-to-fuse distances kept equal. Therefore, high-integration of fuse bodies is achievable without causing damage to adjacent fuse bodies.
A second feature of the present invention lies in a semiconductor device which has a fuse area comprised of a guard ring arranged in the peripheral part of the fuse area; fuse windows arranged within the guard ring; a plurality of dummy interconnections traversing the guard ring and fuse windows. And specific dummy interconnections in the fuse area can be selectively blown away to bring them into a disconnected state. Namely, each dummy interconnection comprising: a first fuse wiring having a first terminal portion; a second fuse wiring having a second terminal portion with a given distance apart from the first terminal portion, being arranged along the same direction as the first fuse wiring is extending; a first connecting member arranged on the first terminal portion; a second connecting member arranged on the second terminal portion; and a fuse body arranged on the first and second connecting members so as to electrically connect the first and second connecting members with each other, having a length not shorter than the given distance and not exceeding a diameter of laser beam used for blowing off the fuse body.
According to the second feature of the present invention, the heat caused by irradiation of the laser beam used for selectively blowing off to bring specific dummy interconnections in the fuse area into a disconnected state is not transported away by conduction in the longitudinal direction of the first and second fuse wiring. Further, a possibility becomes low for the light irradiation to cause damage to adjacent fuse bodies scheduled to be not blown, and even if pitch between the fuse bodies is scaled down, a possibility to cause damage to non-irradiated part becomes low. Especially, all the fuse bodies can be kept at equal minimum intervals to other most adjacent fuse bodies. Further, it is also possible to reduce fuse pitch with the minimum fuse-to-fuse distances kept equal. Therefore, high-integration of fuse bodies and reduction in fuse area are achievable without causing damage to adjacent fuse bodies. Moreover, since the fuse area can be changed in the shape, a selectivity and a degree of freedom in arrangements of other circuits around the fuse area can be improved.
A third feature of the present invention lies in a semiconductor device having a plurality of fuse areas, each of fuse areas is related to the second feature. As described in the second feature, each fuse area is comprised of a guard ring arranged in the peripheral part of the fuse area; fuse windows arranged within the guard ring; a plurality of dummy interconnections traversing the guard ring and fuse windows. Then, it is possible to selectively blow off specific dummy interconnections in at least one of the plural fuse areas to a disconnected state by using a laser beam. Namely, each dummy interconnection comprising: a first fuse wiring having a first terminal portion; a second fuse wiring having a second terminal portion with a given distance apart from the first terminal portion, being arranged along the same direction as the first fuse wiring is extending; a first connecting member arranged on the first terminal portion; a second connecting member arranged on the second terminal portion; and a fuse body arranged on the first and second connecting members so as to electrically connect the first and second connecting members with each other, having a length not shorter than the given distance and not exceeding a diameter of laser beam used for blowing off the fuse body.
According to the third feature of the present invention, the heat generated by irradiation of the laser beam used for selectively blowing off specific dummy interconnections in the plural fuse areas to bring into a disconnected state is not transported away by conduction in the longitudinal direction of the first and second fuse wiring. Further, a possibility becomes low to cause damage to adjacent fuse bodies scheduled to be not blown, by irradiating selectively a specific fuse with laser beam. Further, even if pitch between the fuse bodies is miniaturized, a possibility becomes low to cause damage to non-irradiated part. Therefore, high-integration of fuse bodies and reduction in fuse area are achievable without causing damage to adjacent fuse bodies. Moreover, since the plural fuse areas can be changed in the shape, a selectivity and a degree of freedom in arrangements of other circuits around the fuse areas can be improved.
A fourth feature of the present invention pertains to a method of manufacturing a semiconductor device which has a plurality of dummy interconnections and is capable of blowing off (a) fuse bodies (body) of specific dummy interconnection(s) by using a laser beam and selectively bringing them (it) into a disconnected state. Namely, the method of manufacturing the semiconductor device related to the fourth feature of the present invention consists of, at least (a) forming a plurality of first fuse wiring, each having first terminal portion and a plurality of second fuse wiring, each having second terminal portion with a given distance apart from the first terminal portion; (b) depositing a first interlayer insulating film on the first and second fuse wirings; (c) making contact holes in the first interlayer insulating film to expose a part of the first and second terminal portions; (d) burying conductive material into the contact holes to form first and second connecting members on the first and second terminal portions, respectively; (e) forming a plurality of fuse bodies, each having side lengths not exceeding a diameter of laser beam on the first and second connecting members so as to electrically connect the first and second connecting members with each other; (f) depositing a second interlayer insulating film on the fuse bodies; (g) forming a concave to provide a fuse window at the surface of and in the second interlayer insulating film; and (h) irradiating laser beam through the fuse window to selectively blow off a specific fuse body among the plurality of fuse bodies.
According to the fourth feature of the present invention, when specific fuse body (or bodies) is (are) irradiated with a laser beam, the heat generated by this irradiation of the laser beam is not transported away by conduction in the longitudinal direction of the first and second fuse wirings. Further, a possibility becomes low to cause damage to fuse bodies of adjacent dummy interconnections by irradiating of laser beam. Therefore, it is possible to enhance a manufacturing yield of a product according to the fourth feature of the present invention. Further, even if pitch between the fuse bodies is made narrow, there is little possibility to cause damage to non-blowing part, therefore, reduction in fuse area and chip size can be achieved. As a result, high-integration of fuse bodies and reduction in a fuse area can easily be achieved without causing damage to adjacent fuse bodies.
Other and further objects and features of the present invention will become obvious upon an understanding of illustrative embodiments about to be described in connection with the accompanying drawings or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employing of the invention in practice.